/*首页*/
      #header{
                width:1300px;
                height:50px;
                border:1px soild red;
                background:#00cccc;
            }
            #div1{
                 float:left;
                line-height: 50px;
                font-size: 20px;
            }
            #div2{
                float:right;
                line-height: 50px;
                font-size: 20px;
            }
             #div3{
                 width:300px;
                 height:300px;
                margin-top: 80px;
                margin-left: 100px;
            }
            
